Cigarettes, cigars and pipes are popular smoking articles which use tobacco in various forms. Many improvements and alternatives to these smoking articles have been proposed through the years.
Various methods for altering the composition of mainstream tobacco smoke have also been proposed. For example, many tobacco substitutes can be found in U.S. Pat. No. 4,079,742 (Rainer et al.). In addition, tobacco substitute smoking materials having the tradenames Cytrel and NSM were introduced in Europe during the 1970's.
A number of patents have proposed articles which were said to generate flavored vapor and/or visible aerosol. Most of such articles have employed a combustible fuel source to provide an aerosol and/or to heat an aerosol forming material. See, for example, the background art cited in U.S. Pat. No. 4,714,082 (Banerjee et al.)
Smoking articles which are capable of providing the pleasures associated with cigarette smoking, by heating but not necessarily burning tobacco, and without delivering considerable quantities of incomplete combustion products, are described in the following U.S. Patents, the disclosures of which are hereby incorporated herein by reference; U.S. Pat. Nos. 4,708,151 (Shelar), 4,714,082 (Banerjee et al.), 4,732,168 (Resce et al.), 4,756,318 (Clearman et al.), 4,793,365 (Sensabaugh et al.), 4,819,665 (Roberts et al.), 4,827,950 (Banerjee et al.), 4,854,331 (Banerjee et al.), 4,858,630 (Banerjee et al.), 4,881,556 (Clearman et al.), 4,893,639 (White), 4,903,714 (Barnes et al.) and 4,938,238 (Barnes et al.).
These smoking articles employ a combustible fuel element for heat generation; and aerosol forming substances positioned physically separate from, and in a heat exchange relationship with, the fuel element. The aerosol generating means normally includes tobacco in various forms such as densified pellets, tobacco powder and tobacco extracts, as well as tobacco flavor modifiers and tobacco flavoring agents and aerosol forming substances such as glycerin. During smoking, heat generated by the fuel element acts to volatilize the aerosol forming substances, thereby providing an aerosol which resembles tobacco smoke. Such smoking articles yield extremely low levels of visible sidestream smoke as well as low levels of FTC "tar".
In U.S. Pat. No. 4,756,318 to Clearman et al., there is disclosed a smoking article (cigarette) comprising a short fuel element, a physically separate aerosol generating means and a mouthend piece, which includes a tobacco jacket surrounding at least a portion of the aerosol generating means. As discussed therein at Col. 15, line 60-Col. 16, line 35, the tobacco jacket may also contain glass fibers, which may be in sheet, strip, or tube form. Tobacco sheets containing glass fibers are described as being prepared using conventional paper making techniques, and the amount of glass incorporated into such material is said to range from about 30 to about 70 weight percent.
Improvements in smoking articles such as those described in Clearman et al. are clearly desirable. The present invention represents such an improvement.